Piezoelectric-powered gun firing mechanism



3, 1965 w. E. PERKINS 3,198,074

PIEZOELECTRIC-POWERED GUN FIRING MECHANISM Filed April 30. 1964 INVENTOR. WILLIAM E. PERKINS WdL wAZ W X W ATTORNEYS" United States Patent 3,193,074 PIEZQELEKITRIC-lW/VERED GUN FTREING MECHANlSli i Wiliiam E. Perkins, liunnenrede, Ni, assignor to the United States of America as represented by the Secretary of the Army Fiied Apr. 30, 1964, Ser. No. 364,046 6 Claims. (Cl. 89-12) (Granted under Title 35, US. Code {1052), see. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to a rotary multi-barreled or Gatling type gun, and more particularly to a firing or bolt mechanism therefor. It is an object of this invention to provide an improved mechanism of this type which operates to reduce the number of misfires which this type of rapid fire gun has been prone to have in the past. Another object of this invention is to simplify the bolt operation in such guns and provide the bolt for each barrel with a direct power source for its operation and for longer operating life.

The present invention is based upon a more precise discovery of the cause of misfires in guns of this type and involves providing a simpler and more reliable means for preventing its occurrence when using electrical firing control. For example, a plastic cam contact assembly has been known to be a weak link in the operation of this type of gun. Its useful life is generally only about 6000 rounds. Operation for a longer time causes a noticeable increase in the number of misfires. Eiforts to prolong the life of this plastic cam contact have not been successful because a satisfactory wear-resisting insulating material has not been found.

In accordance with the present invention, the plastic cam contact means having the function of making and breaking an electric circuit between a power source and an electric primer in each round being fired, may be eliminated entirely. In its place a piezoelectric power source is provided and adapted to be mounted in the bolt for each barrel being fired, and each bolt is further provided with a simple stress applicator readily carried thereby without substantially changing its length, breadth or thickness or changing the size of the guide channels in which the bolt moves.

Further in accordance with the invention, advantage is taken of the fact that materials containing lead-styphnate are voltage sensitive. By that is meant that they do not require as large an energy input for firing the primer as other electric primers may need. Therefore, further in accordance with the present invention, instead of making and breaking an electric circuit carrying a substantial energy input between a source of energy remote from each bolt and its firing pin, a power source is provided which is adapted to be carried by each bolt. Not only is the wear less where each bolt has to fire l/ nth of the time the plastic cam has to operate, where n is the number of barrels, but this improved system requires much less energy which can be derived from a crystal. In developing the improved system, it has been found that a piezoelectric crystal may be placed in each bolt and such crystal made to have an output of less than 1% of the energy a piezo crystal would have to provide for an electric primer of other than a styphnatc type. Tests have shown that an electrical energy output for the leadstyphnate type primer requires only 980 ergs. charged to 700 volts directly without any storage capacitor, as against 512,000 ergs. previously with a capacitor.

The invention will further be understood from the following description of a present preferred embodiment,

when considered with reference to the accompanying drawings and its scope is pointed out in the appended claims.

In the drawings:

FIG. 1 is a partial exploded view of a six-barreled Gatling type gun having firing or bolt mechanisms embodying the invention,

FIG. 2 is a side view of one of the firing or bolt mechanisms in an unlocked position,

FIG. 3 is a sectional view of the mechanism of FIG. 2, taken on the line 3 3, and showing further details thereof,

PEG. 4 is a side view of the firing or bolt mechanism of FIG. 1 in a locked position, and

PEG. 5 is a sectional view of the mechanism of FIG. 4, taken on the line 55, and showing further details thereof.

Referring to the drawings, wherein like parts throughout the various figures are designated by like reference numerals, and referring particularly to FIG. 1, there is shown the partial and exploded view of a portion of a gun iii of the Gatlin type in which are provided a plurality of firing mechanisms or bolts 11 embodying the invention. The gun also embodies a corresponding plurality of gun barrels l3 rotatable about a central axis and driven by a gear 14 from a motor (not shown). Within a stationary housing 16 is a rotor 15 containing a plurality of straight firing control channels 1& there being one bolt 11 for each such channel and for each gun barrel. The housing 1.6 is bolted to a housing retainer and bearing 17 for the barrels 13. This is shown in a retracted position from a thrust bearing 14a. On an inner surface of the housing 16 is a groove 18 extending both longitudinally and angularly for 360 in which all of the bolts are guided and stopped for the firing of each bolt and its barrel, a bolt shaft 12 of each bolt being guided within the groove =18 while the body 23 of each bolt rotates with the rotor 15. The apparatus FIG. 1 is shown to exemplify a suitable mechanism for actuating the several bolts shown in FIGS. 2 to 5 to which attention is now directed.

The firing mechanism or bolt 11 shown in PK}. 2 may be of the same width, length, and depth as normally used and may be operated in substantially the same manner, having been modified by incorporation therein of a piezoelectric crystal and mechanism for compressing the crystal. As referred to in FIG. 1, the bolt shaft 12 extends into the body 23 of the bolt for pressing down upon a locking block 24. This block is caused thereby to move about its pivot 25 by a pin 26 movable in a short slot 27 and swing back to its locked position of FIG. 4. This provides for longitudinally holding the bolt in its locked position for firing the gun barrel to which this bolt belongs. As the bolt shaft 12 is moved inwardly (downwardly in PEG. 2), a lever 22 pivoted as shown at 21 in N68. 3 and 5 is moved a short angular distance in a counter clockwise direction causing the upper end of lever 22 to press against a dual-unit piezoelectric crystal 2%, in two sections as indicated, to generate a voltage that is generally proportional to the degree of compressive stress applied to the crystal. The latter may be a single unit. The dual unit provides for added current or voltage output depending upon whether a series or parallel connection is used, as is known. The voltage output, in this case, is applied to a firing pin 2.) through a conductor (not shown) but which may be embedded in the electrical insulating material 36 shown as surrounding both the crystal 23 and the firing pin 29. One side is grounded through a metal disk 28a and the lever 22 to complete the firing circuit. As the shaft 12. moves inwardly (downwardly) from the unlocked position shown in FIG. 2 to the locked or firing position shown in FIG. 4, the lever 22 is moved by a cam or cam surface 39 (FIGS. 2 and 4) into a recess 31 in the bolt body applying stress to the crystal 2-8 and voltage to the firing pin 29. As shown in FlGS. 3 and 5, the lever 22 is connected with a firing-pin actuator lever 32, pivoted at 33, by a tension member or link 34-.

After firing a round the bolt shaft 12 is raised, thereby removing stress from the crystal 28 as the lever 22. is moved in a limited clockwise direction, and a firing pin spring 2i moves the firing pin 29 to the right, as viewed in the drawings, effecting a clockwise rotation of the actuator lever 32 and assisting in moving the lever 22 also in a clockwise direction. As the crystal 2% is relieved of stress, it gives oli a voltage which is opposite to that applied for firin In order that no portions of the bolt may function as a capacitor to store any charge which is opposed to that for firing a round, a discharge pin 35 is applied to or touches the firing pin 29 to carry off any opposite charge to that used in firing.

As shown in FIGS. 2 and 4 the bolt body 23 carries a suitable extractor lip 23a as is normal, although when a caseless or frangible, or consumable case is used for propellant, such lip is not necessary. The insulating material 36 is shown surrounding both the crystal 28 and the firing pin 2% except that when the firing pin is fully retracted, the discharge pin 35 electrically contacts the pin From the foregoing description, it will be seen that a longer operating L fe may be attained, and a compact selfcontained electric power source is provided in each firing mechanism or bolt, with actuating and switching mechanism for this power source also self contained in the same bolt without increase in any of the overall dimensions. Advantage is taken of the voltage sensitivity of lead styphnate type primers and their need for much less electrical energy than has been previously required with electric primers in general, and also of the fact that a piezoelectric crystal, such as that of the bariumtitanate type, can be made there to deliver high enough voltage to be fully effective without an electrical capacitor or storage device in the supply circuit.

Furthermore, the present invention provides a greater degree of reliability in operation, as well as simplification in the distribution and the application of firing current or voltage to the individual moving firing or bolt mecha- I nisms. Thus each bolt operates in a conventional or normal manner as it would if entirely mechanical, while at the same time it provides by its own movement, in each case, for the generation and application of electrical firing voltage to the ammunition being fed through the gun. Otherwise, as has been the case previously, a common power supply means for all the bolt mechanisms must provide operating voltage through switch means and a distribution system involving moving contacts and added complications affecting reliable operation over extended periods of time.

I claim:

1. The combination with a gun for firing ammunition having sensitive electrical primers, of a barrel bolt containing an electric firing pin movable to a position to fire said ammunition from a locked firing position of said bolt, a self-contained power unit in said bolt including a piezoelectric crystal element connected to apply a firing voltage to said firing pin, means responsive to movement of the bolt to said locked position for compressing said crystal element to generate said voltage, means connected with said last-named means for moving said firing pin to said firing position in response to compression of said 4 crystal element and voltage generation, and means for moving said bolt between said locked position and an unlocked position.

2. In a rapid-fire gun, a bolt for a gun barrel thereof comprising a ,bolt body, a movable electric firing pin mounted in said body, a self-contained piezoelectric power unit in said body including a piezoelectric crystal element electrically connected with said firing pin to apply operating voltage directly thereto, movable operating means carried by said body and connected to apply a compressional force to said crystal element for generating said operating voltage in response to movement of said bolt to a locked firing position with respect to said barrel, and means for moving said firing pin in response to movement of said operating means to apply said voltage externally of said bolt in connection with a round of ammunition to be fired in said barrel.

3. A bolt for a gun barrel as defined in claim 2, wherein the movable operating means for compressing the crystal element includes an elongated bolt shaft movable into the body from an unlocked to a locked firing position with the bolt and having a cam element movable therewith, a first lever pivotally movable in connection with said cam element to apply said compressional force to said crystal element, and wherein the means for moving the firing pin includes a second pivoted lever linked with the first lever within the body of the bolt and engaging the firing pin at its inner end to move it outwardly in an axial direction, and compression spring means connected with the firing pin to retract it in the opposite axial direction.

t. The combination with a gun for firing ammunition having sensitive electrical primers, of a barrel bolt containing an electric firing pin movable to a firing position therein, a self-contained power uint in said bolt including a piezoelectric crystal element connected to apply a firing voltage to said firing pin, and means responsive to movement of the bolt to a firing position in the gun for cornpressing said crystal element and generating said voltage in timed relation to the firing pin movement.

5. In a rapid-fire gun to the Gatling type having a plurality of gun barrels in parallel relation and mounted to revolve successively into a firing position in circular formation about a common axis parallel to said barrels, the combination of a housing for the rear ends of said barrels, said housing having a guide groove therein, a movable operating belt for each barrel, each bolt having an operating bolt shaft movable in and guided by said groove and being locked in the firing position or" each barrel, a piezoelectric crystal element carried by each bolt, an electric firing pin in each bolt connected to the crystal element therein for receiving a firing voltage from said element, and means connected with the bolt shaft in each bolt for applying a voltage-generating pressure to the crystal element therein in response to movement to the firing position of the bolt and barrel associated therewith.

6. In a rapid-fire gun of the Gatling type, the combination as defined in claim 5, wherein the pressure applying means includes a pivoted lever having contact with the crystal element and a bolt shaft in each bolt for limiting the applied pressure to relatively low values for a voltage output adapted for effective firing of ammunition of the type having styphnate and like voltage-sensitive primers.

No references cited.

BENJAMIN A. BORCHELT, Primary Examiner. 

5. IN A RAPID-FIRE GUN TO THE GATLING TYPE HAVING A PLURALITY OF GUN BARRELS IN PARALLEL RELATION AND MOUNTED TO REVOLVE SUCCESSIVELY INTO A FIRING POSITION IN CIRCULAR FORMATION ABOUT A COMMON AXIS PARALLEL TO SAID BARRELS, THE COMBINATION OF A HOUSING FOR THE REAR ENDS OF SAID BARRELS, SAID HOUSING HAVING A GUIDE GROOVE THEREIN, A MOVABLE OPERATING BOLT FOR EACH BARREL, EACH BOLT HAVING AN OPERATING BOLT SHAFT MOVABLE IN AND GUIDED BY SAID GROOVE AND BEING LOCKED IN THE FIRING POSITION OF EACH BARREL, A PIEZOELECTRIC CRYSTAL ELEMENT CARRIED BY EACH 